Cartrack leaving no tracks of commitments !

I purchased a second hand car from somebody else in November 2022. We agreed that I will take over the Cartrack device installed in the vehicle. I completed the necessary forms as provided by the previous owner and e-mailed to Cartrack. Unfortunately I did not receive any response and hence I paid Cartrack's offices a visit on 29 November 2022. I was assisted by a friendly lady and re-completed the "transfer of owner" forms, paid the R350 for "change of owner" and organised for the monthly debit order. The debit order went through successfully on 2 Jan 2023. I also received a "certificate of installation" after I had to remind Cartrack a few times that I had requested such. To my dismay the previous owner is now receiving e-mails demanding the R350 be paid. This is unacceptable! What more can I do? Clearly somebody is not doing their job at Cartrack. Should this matter not be resolved, I will shop around for a tracking device company who is serious about bussiness.